Ground Test facilities that can operate with Mach numbers changing continuously within a predetermined range are critical for the development of supersonic and hypersonic engine and vehicle technologies. A Mach range of 3-8, for example, covers a transition from turbine engines to ramjet engines (Mach 3-4), and from ramjet engines to scramjet engines (Mach 5-6). A continuously changing Mach range also produces changes in shock angle. Current ground-based testing facilities are unable to efficiently produce continuous testing over predetermined Mach ranges.
The majority of current ground-testing facilities operate at a fixed Mach number. Ground testing facilities utilizing rectangular geometries with flat plates configured to rotate around fixed locations have been proposed. However, flat plates require problematic sliding seals to contain extremely hot flow path gases and can only produce rectangular flow paths. The shape restrictions of rectangular flow paths precludes achieving optimally conditioned flow over the entire predetermined Mach range.